According to the Archives of Vacheron Constantin, the present watch was manufactured in 1960.
World Time watches
As of the 1930s, Vacheron Constantin produced world time watches with varying case designs and dial layouts, the majority however featuring an openface case. Hunter cased "World Time" watches, such as the present example, are exceedingly rare.
The world time mechanism was invented by celebrated Geneva watchmaker Louis Cottier (1894-1966). The technology was incorporated into watches by several of Switzerland's leading watch firms, including Vacheron Constantin, Patek Philippe and Rolex.
The world time mechanism is a functional complication simple to calibrate. One must first set the local or mean time through the crown (the 24 hour ring will revolve in the opposite direction of the hands). Then the outer ring is adjusted by depressing the button in the band until one's current global location is indicated at the 12 o'clock position. Once this is calibrated, the relative time of each world location is set. The two-tone 24-hour ring indicates world locations that are in night time by the grey section and daytime by the silvered section.